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4 và 2/5 + 5 và 6/9 +2 và 3/4 + 3/5+1/3+1/4
= 22/5+51/9+11/4+3/5+1/3+1/4
=(22/5+3/5)+(51/9+1/3)+(11/4+1/4)
=25/5+54/9+12/4
=5+6+3
=14
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\(\frac{1}{3}+\frac{1}{2}=\frac{2}{6}+\frac{3}{6}=\frac{5}{6}\)
\(3\times\frac{1}{2}=\frac{3}{1}\times\frac{1}{2}=\frac{3}{2}\)
\(1-\left(\frac{2}{3}+\frac{1}{6}\right)=1-\left(\frac{4}{6}+\frac{1}{6}\right)=1-\frac{5}{6}=\frac{1}{6}\)
\(1\frac{1}{5}\div1\frac{1}{2}=\frac{6}{5}\div\frac{3}{2}=\frac{6}{5}\times\frac{2}{3}=\frac{12}{15}=\frac{4}{5}\)
\(\frac{3}{5}+\frac{2}{5}\times\frac{1}{6}=\frac{3}{5}+\frac{2}{30}=\frac{3}{5}+\frac{1}{15}=\frac{9}{15}+\frac{1}{15}=\frac{10}{15}=\frac{2}{3}\)
3 phần 5 + 2 phần 5 nhân 1 phần 6 là tính día trị của biểu thức
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có : \(\frac{3}{5}+\frac{6}{11}+\frac{7}{13}+\frac{2}{5}+\frac{5}{11}+\frac{19}{13}+\frac{1}{2}+\frac{2}{3}-\frac{1}{6}\)
\(=\left(\frac{3}{5}+\frac{2}{5}\right)+\left(\frac{6}{11}+\frac{5}{11}\right)+\left(\frac{7}{13}+\frac{19}{13}\right)+\left(\frac{1}{2}+\frac{2}{3}-\frac{1}{6}\right)\)
\(=1+1+2+1=5\)
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= (3/5 + 2/5) + (6/11 + 5/11) + (7/13 + 19/13) : 1/2 + 2/3 - 1/6
= (1 + 1 + 2) : (1/2 + 4/6 - 1/6)
= 4 : (1/2 + 1/2)
= 4 : 1
= 4
Vậy kết quả bằng 4
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\(a.32,5-3\cdot0,87=32,5-2,61=29,89\)
\(8,5\cdot\left(1\dfrac{1}{2}+\dfrac{4}{4}\right):5=8,5\cdot\left(\dfrac{3}{2}+\dfrac{4}{4}\right):5\\ =8,5\cdot\left(\dfrac{6}{4}+\dfrac{4}{4}\right):5\\ =8,5\cdot\dfrac{10}{4}:5\\ =\dfrac{85}{4}:5\\ =\dfrac{17}{4}\)
\(b.30,96-6,45+14,4:3=30,96-6,45+4,8\\ =29,31\)
\(\dfrac{2}{5}\cdot\left(\dfrac{4}{5}-\dfrac{1}{2}\right)=\dfrac{2}{5}\cdot\left(\dfrac{8}{10}-\dfrac{5}{10}\right)\\ =\dfrac{2}{5}\cdot\dfrac{3}{10}=\dfrac{3}{25}\)
bài 2
\(a.2,5\cdot12,5\cdot8\cdot0,4=\left(2,5\cdot0,4\right)\left(12,5\cdot8\right)\\ =1\cdot100=100\)
b,\(\dfrac{12}{15}\cdot\dfrac{5}{6}\cdot\dfrac{3}{20}\cdot\dfrac{32}{5}=\dfrac{12\cdot5\cdot3\cdot32}{15\cdot6\cdot20\cdot5}\\ =\dfrac{3\cdot4\cdot5\cdot3\cdot4\cdot8}{3\cdot5\cdot2\cdot3\cdot5\cdot4\cdot5}=\dfrac{16}{25}\)
Bài 1:
a) \(32.5-3\cdot0.87=32.5-2.61=29.89\)
\(8.5\cdot\left(1\dfrac{1}{2}+\dfrac{4}{4}\right):5=8.5\cdot\dfrac{5}{2}:5=\dfrac{17}{2}\cdot\dfrac{5}{2}:5=\dfrac{85}{4}\cdot\dfrac{1}{5}=\dfrac{17}{4}\)
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5/6x1/3+1/2x3/4x5/3
=5/18+3/8x5/3
=5/18+15/24
=5/18+5/8
=130/144=65/72
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\(\left(1-\dfrac{1}{2}\right)\times\left(1-\dfrac{1}{2}\right)\times\left(1-\dfrac{1}{3}\right)\times\left(1-\dfrac{1}{4}\right)\times\left(1-\dfrac{1}{5}\right)\)
\(=\dfrac{1}{2}\times\dfrac{1}{2}\times\dfrac{2}{3}\times\dfrac{3}{4}\times\dfrac{4}{5}\)
\(=\dfrac{1}{2}\times\dfrac{1}{5}\)
\(=\dfrac{1}{10}\)
bằng 31/30 nhé
TL :
\(\frac{1}{2}+\frac{1}{3}+\frac{1}{5}=\frac{3}{6}+\frac{2}{6}+\frac{1}{5}=\frac{5}{6}+\frac{1}{5}=\frac{25}{30}+\frac{6}{30}=\frac{31}{30}.\)
HT